For the past week or so, I have been plagued with SMTP timeout errors - I have tried 3 different SMTP's and the issue does not resolve - Hence I feel it is Thunderbird/Host Computer/ or internet connection related, rather than anything external -

Messages with this error do not send, but end up in my "sent" folder which is not helping as often I am not sure if an email has sent or not - When I try to resend the message from the "sent" folder, it often sends without issue.The problem is more pronounced it seems when sending larger attachments (max 6mb) or if I am replying to a long conversation - So I am wondering if it could be to do with gif signatures, and attachments - Anyway - some guidance would be appreciated - This has only been recently happening, and my email flow/recipients/email content has not changed much for 3 years.

How is the account set up in Thunderbird, as POP or IMAP? Find out using menu path Tools->Account Settings->Server Settings->Server Type at the top right of the dialogue.Do you have the security software you are running on that system set to NOT scan outgoing messages?

How is the account set up in Thunderbird, as POP or IMAP? Find out using menu path Tools->Account Settings->Server Settings->Server Type at the top right of the dialogue.Do you have the security software you are running on that system set to NOT scan outgoing messages?

Hi Dan - It is set up IMAPI am using Windowws Defender, and I do not think it scans email - All of my email is also sent to Gmail which sends me warnings of any malicious content - it is quite thorough.

Well, the point of asking about scanning outgoing messages was not about malicious content but the potential for those scans to delay sending to the point that the connection to the server times out. Apparently that is not a factor in this case.

Do you access that Gmail account from more than one computer and require access to sent messages when doing so? If not, you could change the target for saving Sent messages to the Sent folder on the local computer (Tools->Account Settings->Copies & Folders) to eliminate any lag due to storing the outgoing messages on the Gmail servers.

Run a internet speed test such as http://beta.speedtest.net/ and see if the results are close to what you expect. I suggest you also ping the SMTP mail server from a console window (use CMD to create one) and see if it loses data. For example:

If you are using a Gmail SMTP server you should not configure that account in Thunderbird to save a copy (either locally or remote) as the Gmail SMTP server always saves a copy in the remote "sent mail" folder.

DanRaisch wrote:Well, the point of asking about scanning outgoing messages was not about malicious content but the potential for those scans to delay sending to the point that the connection to the server times out. Apparently that is not a factor in this case.

Do you access that Gmail account from more than one computer and require access to sent messages when doing so? If not, you could change the target for saving Sent messages to the Sent folder on the local computer (Tools->Account Settings->Copies & Folders) to eliminate any lag due to storing the outgoing messages on the Gmail servers.

Sorry - My information was misleading - All sent items are stored on a local folder only (current size 6gb odd) - The gmail only holds copies of incoming messages - Sorry for the confusion.

tanstaafl wrote:Run a internet speed test such as http://beta.speedtest.net/ and see if the results are close to what you expect. I suggest you also ping the SMTP mail server from a console window (use CMD to create one) and see if it loses data. For example:

If you are using a Gmail SMTP server you should not configure that account in Thunderbird to save a copy (either locally or remote) as the Gmail SMTP server always saves a copy in the remote "sent mail" folder.

Hi - I tried this with the three SMTP server options I have No packet loss

tanstaafl wrote:Run a internet speed test such as http://beta.speedtest.net/ and see if the results are close to what you expect. I suggest you also ping the SMTP mail server from a console window (use CMD to create one) and see if it loses data. For example:

If you are using a Gmail SMTP server you should not configure that account in Thunderbird to save a copy (either locally or remote) as the Gmail SMTP server always saves a copy in the remote "sent mail" folder.

Hi - I tried this with the three SMTP server options I have No packet loss

I would try to get the actual Sent folder down to something under 1GB. Be sure to compact that folder after all messages to be archived are safely copied into new locations.

Thank you - I have indeed created a new subfolder in the local sent folder and things seem to be working better (fingers crossed) - Seems 6GB is just a bit too large for a local sent subfolder.

Thank you for all your help

Unfortunately this issue is still ongoing - It was a coincidence that creating a new sent folder temporarily solved this issue - I am still having issues sending email almost every time - I cannot seem to find a cause of the time out errors. Currently running TB in safe mode to see if that improves anything. Meanwhile, if anyone else has an idea for this, please chime in.

Are you able to open message with large attachments, in your inbox? The reason I ask is if you are having connection problems I'd expect them to also effect the IMAP account.

Are you using a WiFi connection to a router or a Ethernet connection? A couple of times a similar problem has been traced to the router settings when using WiFi. I never got the details on exactly what was changed though. Perhaps it was just a poor signal.

tanstaafl wrote:Are you able to open message with large attachments, in your inbox? The reason I ask is if you are having connection problems I'd expect them to also effect the IMAP account.

Are you using a WiFi connection to a router or a Ethernet connection? A couple of times a similar problem has been traced to the router settings when using WiFi. I never got the details on exactly what was changed though. Perhaps it was just a poor signal.

Thank you for the reply.

Receiving is no problem - All emails with all sizes of attachment are coming in okI have an ethernet connection + wifi connection to the router (and switching between them does not help the issue) - It is worth mentioning that this is a new issue from around start of November - had 4 years of trouble free sending up to this point